There’s no such thing as a free lunch in this world. Now apparently the same goes for Wi-Fi.

Students in the cafeteria at China’s Nanjing University of Aeronautics and Astronautics must solve a calculus equation to get the school Wi-Fi password, state media Global Times reported Sunday. The password lies within the answer to the problem, according to instructions seen in pictures posted by the student union.

That’s not the only hurdle facing students for internet access across the campus. An eight-note melody containing the password to the Wi-Fi connection awaits students at the school’s Xinyuan Library Restaurant.

‘We chose a music notation problem for the Xinyuan Library Restaurant because [there are] more liberal arts students,’ an employee known only as Ji told the Global Times, adding that a math problem was picked for the cafeteria because there were more engineering students, many of whom have solved the equation.

Despite the challenge, students aren’t worried about their internet access. Users commented on Weibo that once a student solves the equation, they’ll just share the answer and everyone will get their sweet internet access. It’s not known if passwords will remain the same every day, though.

Others suggest the calculus problem is a test of foundation, so you should be able to solve it if you’ve paid attention during class.

‘The students from NUAA are all super nerds. They love new things. It must be fun for them,’ a teacher told the Global Times.